This invention generally relates to a method of joining a heat shrinkable, tubular member to an inner member such as found in the construction of vascular catheters and particularly low-profile steerable catheters for angioplasty procedures.
In classic percutaneous transluminal coronary angioplasty procedures (PTCA), a guiding catheter having a preformed distal tip is first percutaneously introduced into the patient's arterial system and advanced therein until the distal tip of the guiding catheter is disposed in the appropriate ostium of the patient's coronary artery. A guidewire is preloaded within an inner lumen of a dilatation catheter and both are advanced through the previously positioned guiding catheter to the distal end thereof. The guidewire is first advanced out of the distal end of the guiding catheter into the patient's coronary anatomy until the distal end of the guidewire crosses the stenotic region to be dilated. The dilatation catheter is then slidably advanced out the distal tip of the guiding catheter over the guidewire into the patient's coronary artery until the balloon on the dilatation catheter is positioned within the stenosis. The balloon is inflated to a relatively high pressure (e.g. up to 8 atmospheres or more) to dilate the stenosis and then deflated and removed over the guidewire. For a detailed description of procedures, reference is made to U.S. Pat. No. 4,332,254 (Lundquist), U.S. Pat. No. 4,323,071 (Simpson-Robert), U.S. Pat. No. 4,411,055 (Simpson-Robert), U.S. Pat. No. 4,439,185 (Lundquist), U.S. Pat. No. 4,468,224 (Enzmann et al.), U.S. Pat. No. 4,516,972 (Samson), U.S. Pat. No. 4,538,622 (Samson et al.), U.S. Pat. No. 4,554,929 (Samson et al.), U.S. Pat. No. 4,569,347 (Frisbie), U.S. Pat. No. 4,571,240 (Samson et al.), U.S. Pat. No. 4,638,805 (Powell), U.S. Pat. No. 4,748,982 (Horzewski et al.), all of which are hereby incorporated herein in their entirety by reference thereto.
Steerable dilatation catheters with built-in or fixed guidewires or guiding members are frequently used because the deflated profile of such catheters are generally much smaller than conventional over-the-wire type dilatation catheter system described above having the same inflated balloon diameter. Further details of steerable fixed wire dilatation catheters may be found in U.S. Pat. No. 4,582,181 (Samson) which is hereby incorporated herein in its entirety by reference thereto. The lower profile of these catheters allows them to cross tighter lesions and to be advanced much deeper into the patient's coronary anatomy than over-the-wire type catheters.
With most dilatation catheters, the distal ends of the balloons are bonded to an inner guiding member or an inner tubular member by a suitable adhesive. However, this bond may require relatively large amounts of adhesive material, frequently making the catheter stiff at this bond location, particularly with steerable, fixed wire catheters.
What has been needed and heretofore unavailable is a method of sealingly bonding the distal end of the balloon on an intravascular catheter such as used is angioplasty procedures to an inner member so that the joint has a greater degree of flexibility and a lower profile. The present invention satisfies that need.